The present invention relates to automatic transmissions and, more particularly, to a governor spring bracket assembly, which functions to counterbalance the centrifugal force acting on the governor valve weights in order to assist in the return stroke of the governor valve weight in a shaft-mounted governor. Applications for the present governor spring bracket assembly include the Chrysler A413, A404, A470, and A670 transmissions.
Automatic transmission systems of the prior art have a hydraulic circuit sub-system which includes at least a hydraulic pump, a valve body having fluid conducting passages or circuits, input and exhaust ports formed within the fluid circuits, and a plurality of spool valves so-called because of their resemblance to sewing thread spools. Such valves are comprised of cylindrical pistons having control diameters or lands formed thereon, which alternately open and close the ports to regulate the flow and pressure of automatic transmission fluid (hereinafter “ATF”) within the fluid circuits to actuate different components of the transmission. It will be understood that in describing hydraulic circuits, ATF usually changes names when it passes through an orifice or control valve in a specific circuit.
In such an automatic transmission the governor valve assembly (hereinafter “governor”) functions to vary transmission fluid pressure based on output shaft rotational speed (i.e. road speed). When governor pressure overcomes throttle pressure, an upshift takes place. Thus, maintaining fluid pressure within the governor circuit is critical to proper shift timing in the transmission.
The governor on the Chrysler transmissions is a shaft-mounted type governor that uses centrifugal force acting on the governor valve weights or pistons (hereinafter “weights”) to vary governor output pressure. As the vehicle begins to move and the transmission output shaft turns, centrifugal force begins to act upon the weights causing them to move radially outward away from the output shaft. As this happens the line pressure inlet ports formed in the governor begin to open and the exhaust ports close. This causes the governor fluid outlet to release ATF at line pressure to other valve assemblies within the governor circuit. When output shaft speed decreases, the weights (assisted only by hydraulic pressure) move back toward the output shaft closing the inlet ports and opening the exhaust ports thereby lowering governor output pressure.
In the Chrysler transmissions a problem arises when the governor weights stick in the governor leaving the inlet ports open after output shaft speed drops to 0 rpm. Even the slightest inlet port opening will result in governor output pressure stroking the 1–2 shift valve, which causes a second gear start.
Thus, the present invention has been developed to resolve this problem and other shortcomings of the prior art.